Compounds containing phosphorous and a method for making polycarbodiimide foams with the compounds as a catalyst

ABSTRACT

A compound adapted to be used to advantage as a catalyst for making carbodiimide foams is prepared by a process wherein 
     (a) a phosphetane oxide or phosphetane sulphide of the general Formulae I and II: ##STR1## wherein X represents a C 1  -C 18  alkyl, C 2  -C 18  alkenyl, C 6  -C 14  aryl, C 7  -C 20  aralkyl, C 1  -C 18  alkoxy or C 6  -C 14  aroxy group and 
     R 1  to R 6  represent hydrogen and/or C 1  -C 4  alkyl groups and is reacted with 
     (b) a mono-, di- and/or polyhydric alcohol having a molecular weight of about 32 to about 250, a protonic acid which has a pH of between 1 and 8 in N/10 aqueous solution, a metal salt or an acid chloride.

This is a division of application Ser. No. 498,788, filed Aug. 19, 1974,now U.S. Pat. No. 3,931,059.

This invention relates generally to polycarbodiimides and moreparticularly to compounds adapted to be used as catalysts in makingpolycarbodiimide foams.

It is known to produce polyurethane foams from organic polyols andorganic polyisocyanates with the aid of catalysts such as tertiaryamines and/or metal compounds. Blowing agents such as water and/ororganic low boiling compounds, preferably halogenated alkanes such asmonofluorotrichloromethane and the like are often used. Thesepolyurethane foams generally have poor flame resistance so it isncessary to add flame retardants, e.g. compounds which containphosphorus and/or halogen, in order to obtain incombustible or flameresistant foams.

Furthermore, it has been disclosed, e.g. in German Pat. No. 1,130,594,that foam plastics with carbodiimide groups which frequently have betterflame resitance than polyurethane foams can be obtained from organicpolyisocynates in the presence of phospholines or their salts andoxides.

In Belgian Pat. No. 567,835, a similar process is described forproducing foam plastics which contain carbodiimide groups frompolyisocyanates in the presence of phospholine oxide as a catalyst.

These processes, however, still have numerous disadvantages which limittheir industrial use, for example, carbodiimide-containing foamsproduced by them which have a substantially closed cell structurecombined with extremely low densities have a strong tendency to shrink.

A further disadvantage which restricts the commercialization of theknown processes lies in the fact that, if low catalyst concentrationsare used, the foams take more than 1 to 2 hours to harden in a heatedmold. Although tough foams can be obtained by a very rapid reaction evenat room temperature if high concentrations of conventional catalysts areused (2 to 5%, based on the quantity of isocyanate), the reactionmixture containing these catalyst concentrations reacts so rapidly thatit becomes difficult in practice to mix the polyisocyanate and catalysthomogeneously and discharge the mixture from the mixing apparatus beforesolidification; i.e. the starting time is too short.

It is also known that phosphetane oxides can be used ascarbodiimidization catalysts.

Unchanged phosphetane oxides, however, are so highly reactive that theyare unsuitable for the production of polycarbodiimide foams.

On the other hand, foams which have a polycarbodiimide structure haveexcellent flame resistance even at low densities so that they are ofconsiderable commercial and economic interest and the solution of theproblems mentioned above therefore constitutes an important technicaladvance.

One method of solving the technical problem mentioned above is disclosedin Belgium Pat. No. 804,855 in the name of the present Applicants.

This earlier application relates to addition compounds of

a. phospholine oxides, phospholine sulphides, phospholane oxides andphospholane sulphides and

b. mono-, di- and/or polyalcohols with molecular weights of 32 to 250 orprotonic acids which have pH values of 1 to 8 in N/10, aqueous solutionor metal salts or acid chlorides

and to the use of these catalysts for producing hard or rigid foamswhich contain carbodiimide groups.

It is an object of this invention to provide a novel and improved methodfor making polycarbodiimide foams. Another object of the invention is toprovide a method for making polycarbodiimide foams which are tough anddimensionally stable. Still another object of the invention is toprovide new polyaddition products which are catalysts for the reactionswhich produce a polycarbodiimide foam.

The foregoing objects and others are accomplished in accordance withthis invention, generally speaking, by providing addition compoundsprepared by reacting

a. a phosphetane oxide or phosphetane sulphide of the general Formulae Iand II: ##STR2## wherein X represents a C₁ -C₁₈ alkyl, C₂ -C₁₈ alkenyl,C₆ -C₁₄ aryl, C₇ -C₂₀ aralkyl, C₁ -C₁₈ alkoxy or C₆ -C₁₄ aroxy group and

R¹ to R₆ represent hydrogen and/or C₁ -C₄ alkyl groups and

b. a mono-, di- and/or polyhydric alcohol having a molecular weight ofabout 32 to about 250, a protonic acid which has a pH of between 1 and 8in N/10 aqueous solution, a metal salt or an acid chloride.

Addition compounds prepared by reacting

(a) 1-Oxo-1,2,2,3,4,4-hexamethyl-phosphetane and

(b) glycerol, ethylene glycol, oxalic acid, phosphorus oxychloride,hydrochloric acid or zinc chloride are particularly preferred catalystsfor making polycarbodiimide foams.

The invention thus provides new catalysts with which tough anddimensionally stable, i.e. non-shrinking foams with a polycarbodiimidestructure can be prepared in a relative short reaction time at roomtemperature.

Any suitable compound prepared from (a) and (b) above may be used toadvantage as a catalyst in the production of polycarbodiimide foams suchas, for example,

(a) 1-Oxo-1,2,2,3,4,4-hexamethylphosphetane and

(b) aluminum chloride;

(a) 1-Oxo-1,2,2,3,4,4-hexamethylphosphetane and

(b) formic acid;

(a) 1-Oxo-1,2,2,3,4,4-hexamethylphosphetane and

(b) sulphuric acid;

(a) 1-Oxo-1,2,2,3,4,4-hexamethylphosphetane and

(b) zinc chloride;

(a) 1-Oxo-1,2,2,3,4,4-hexamethylphosphetane and

(b) zinc acetate;

(a) 1-Oxo-1,2,2,3,4,4-hexamethylphosphetane and

(b) antimony trichloride;

(a) 1-Oxo-1,2,2,3,4,4-hexamethylphosphetane and

(b) phosphorus oxychloride;

(a) 1-Oxo-1,2,2,3,4,4-hexamethylphosphetane and

(b) methane phosphonic acid dichloride;

(a) 1-Thio-1-phenyl-2,2,3,4,4-pentamethylphosphetane and

(b) glycerol;

(a) 1-Thio-1-phenyl-2,2,3,4,4-pentamethylphosphetane and

(b) ethylene glycol; and the like.

The phosphetanes used for preparing the addition compounds according tothe invention are known per se.

The phosphetane oxides and phosphetane sulphides used may be anyphosphorus compound of the following Formulae I and II: ##STR3## whereinX represents a C₁ -C₁₈ alkyl, C₂ -C₁₈ alkenyl, C₆ -C₁₄ aryl, C₇ -C₂₀aralkyl, C₁ -C₁₈ alkoxy or C₆ -C₁₄ aroxy group and

R¹ to R⁶ denote hydrogen and/or C₁ -C₄ alkyl groups.

Examples of suitable phosphorous compounds include:

1-oxo-1,2,2,3,4,4-hexamethylphosphetane,

1-oxo-1-benzyl-2,2,3,4,4-pentamethyl-phosphetane,

1-oxo-1-methoxy-2,2,3,4,4-pentamethyl-phosphetane,

1-oxo-1-t-butyl-2,2,3,4,4-pentamethyl-phosphetane,

1-thio-1-phenyl-2,2,3,4,4-pentamethyl-phosphetane,

1-oxo-1-phenyl-2,2,3,3,4-pentamethyl-phosphetane,

1-thio-1-phenyl-2,2,3,3-tetramethyl-phosphetane,

1-oxo-1-phenyl-2,2,3,3-tetramethyl-phosphetane,

1-oxo-1-methoxy-2,2,3-trimethyl-phosphetane,

1-oxo-1-phenyl-2,2,3-trimethyl-phosphetane,

1-oxo-1-phenyl-2,2,4,4-tetramethyl-3-i-propyl-phosphetane,

1-oxo-1-methoxy-2,3,4,4-tetramethyl-phosphetane and the like.

Any suitable mono-, di- and/or polyalcohol having a molecular weight offrom about 32 to about 250 (component b) may be used for preparing theaddition compounds according to the invention such as, for example,methanol, ethanol, butanol, isopropanol, ethylene glycol, di- andtriethylene glycol, propane-1,3- and -1,2-diol, butane-1,3- and-1,4-diol, glycerol, trimethylolpropane, hexane-1,6-diol,hexane-1,2,6-triol and the like. Preferred polyalcohols are alcoholswith valencies of 3 to 8. Most preferred alcohols are mono-alcohols,diols and triols.

Any suitable protonic acid which has a pH of between 1 and 8 in N/10aqueous solution may be used as component b. Preferred protonic acidsare mono-, di- and/or polycarboxylic acids having a molecular weight ofabout 46 to about 250 and mineral acids known per se. The following areexamples of suitable protonic acids: formic acid, acetic acid, propionicacid, butyric acid, mono-, di- and trichloro-acetic acid, oxalic acid,fumaric acid, maleic acid, adipic acid and the like. Suitable mineralacids are e.g. hydrochloric, hydrobromic and hydriodic acid,o-phosphoric acid, boric acid, sulphuric acid, phosphorous acid and thelike.

Any suitable metal salt may be used as component b such as, for example,zinc chloride, tin(II) bromide, tin(IV) chloride, magnesium chloride,calcium chloride, lithium chloride, lithium iodide, cadmium chloride,manganese(II) chloride, vanadium oxytrichloride and the like. The acidchlorides used (also component b) may be inorganic or hetero organic andmay contain e.g. the elements sulphur, phosphorus, silicon, arsenic andantimony. The following are examples of suitable acid chlorides:phosphorus(III) chloride, phosphorus oxy-tribromide, phosphorusoxychloride, antimony(V) chloride, silicon(IV) chloride, methyltrichlorosilane, methane phosphonic acid dichloride, methane sulphonicacid chloride, p-toluene sulphonic acid chloride and1-chloro-1-oxophospholine and the like.

To prepare the addition compounds according to the invention, component(a) and component (b) are mixed together in a molar ratio of between1:20 and 20:1, preferably between 1:5 and 5:1 and more particularlybetween 3:1 and 1:2. Inert solvents such as benzene, ethyl acetate oracetone and particularly chloroform may be used. The new additioncompounds may be partially isolated by crystallization.

The addition compounds according to the invention are in many cases oilysubstances or crystalline compounds which can be identified e.g. bymeans of their infra red and/or nuclear magnetic resonance spectra or bytheir formation enthalpy.

Distinct shifts in the nuclear magnetic resonance spectrum are obtainedwhen 1-methyl-1-oxophosphetanes are used. The shift in the band positionis given in the examples wherever it is used to identify the compoundsobtained.

This invention also provides a process for the production of additioncompounds which contain phosphorus, characterized in that a

a. Phosphetane oxide or phosphetane sulphide of the general formulae Iand II ##STR4## wherein X represents a C₁ -C₁₈ alkyl, C₂ -C₁₈ alkenyl,C₆ -C₁₄ aryl, C₇ -C₂₀ aralkyl, C₁ -C₁₈ alkoxy or C₆ -C₁₄ aroxy group and

R¹ to R⁶ represent hydrogen and/or C₁ -C₄ alkyl groups is mixed with

b. a mono-, di- and/or polyhydric alcohol having a molecular weight ofabout 32 to about 250 or a protonic acid which has a pH of between 1 and8 in N/10 aqueous solution or a metal salt or acid chloride in a molarratio of 1:20 to 20:1, preferably 5:1 to 1:5 and particularly 3:1 to1:2, optionally in the presence of inert solvents.

By using the addition compounds provided by the invention as catalystsfor the production of foam plastics which contain carbodiimide groups, astarting time sufficiently long for vigorous mixing and discharge of themixture from the mixing apparatus is obtained even at high catalystconcentrations and, once the reaction has begun, conversion of theorganic polyisocyanate to a foam resin which contains carbodiimidegroups can be completed within a short time, even at room temperature. Aparticularly advantageous course of the reaction, i.e. a long startingtime followed by a rapid foaming process, is obtained with thoseaddition compounds in which component (b) is capable of reacting withisocyanates.

The polycarbodiimide foams which can be produced from polyisocyanateswith the aid of the addition compounds according to the inventiongenerally have densities of from 5 to 100 kg/m³, preferably 10 to 30kg/m³, and have stable contours and are distinguished by their excellentdimensional stability under heat and excellent flame resistance. Byflame resistance is meant that the foams are "self-extinguishing"according to ASTM D 1692 or "flame-resistant" according to DIN 4102.

A further object of this invention is therefore a process for theproduction of hard or rigid foam plastics which contain carbodiimidegroups from organic polyisocyanates in the presence of catalysts whichform carbodiimide groups, water and/or organic blowing agents,characterized in that the catalysts used are addition compounds of

a. phosphetane oxide or phosphetane sulphide of the general formulae Iand II: ##STR5## wherein X represents a C₁ -C₁₈ alkyl, C₂ -C₁₈ alkenyl,C₆ -C₁₄ aryl, C₇ -C₂₀ aralkyl, C₁ -C₁₈ alkoxy or C₆ -C₁₄ aroxy group and

R¹ to R⁶ represent hydrogen and/or C₁ -C₄ alkyl groups, and

b. a mono-, di- and/or polyalcohol with a molecular weight of about 32to about 250, a protonic acid which has a pH of between 1 and 8 in N/10aqueous solution, a metal salt or an acid chloride,

in any catalytic amount such as, for example, 0.5% to 20 percent byweight, preferably 1 to 10 percent by weight, based on the quantity ofpolyisocyanate.

According to a special variation of the process of the invention, amixture which is stable when stored at room temperature is prepared froman organic polyisocyanate, a catalyst and optionally conventionalfoaming agents such as emulsifiers and/or stabilizers. The foamingprocess can then be started by simply heating this mixture totemperatures of between 40° and 200° C., preferably 50° to 150° C.

The following addition compounds are examples of preferred catalysts forthis variation of the process: 1-Oxo-1,2,2,3,4,4-hexamethylphosphetaneand hydrogen chloride; 1-oxo-1,2,2,3,4,4-hexamethylphosphetane andphosphorus oxychloride; 1-oxo-1,2,2,3,4,4-hexamethylphosphetane and zincchloride; 1-oxo-1-phenyl-2,2,3,3,4-pentamethyl-phosphetane and calciumchloride.

Any suitable organic polyisocyanate may be used for the processaccording to the invention such as, for example, aliphatic,cycloaliphatic, araliphatic, aromatic or heterocyclic polyisocyanatessuch as those described e.g. by W. Siefken in Justus Liebigs Annalen derChemie, 562, pages 75 to 136, for example, ethylene diisocyanate,tetramethylene-1,4-diisocyanate; hexamethylene-1,6-diisocyanate;dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;cyclohexane-1,3- and -1,4-diisocyanate and any mixtures of theseisomers; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane(German Auslegeschrift No. 1,202,785); hexahydrotolylene-2,4- and-2,6-diisocyanate and any mixtures of these isomers;hexahydrophenylene-1,3-and/or -1,4-diisocyanate;perhydrodiphenylmethane-2,4'- and/or -4,4'-diisocyanate; phenylene-1,3-and -1,4-diisocyanate; tolylene-2,4- and -2,6-diisocyanate and anymixtures of these isomers; diphenylmethane-2,4'- and/or4,4'-diisocyanate; naphthylene-1,5-diisocyanate;triphenylmethane-4,4',4"-triisocyanate;polyphenyl-polymethylene-polyisocyanates which can be obtained byaniline-formaldehyde condensation followed by phosgenation and whichhave been described e.g. in British Pat. Nos. 874,430 and 848,671;perchlorinated aryl polyisocyanates as described e.g. in GermanAuslegeschrift No. 1,157,601; polyisocyanates which contain carbodiimidegroups as described in German Pat. No. 1,092,007; the diisocyanatesdescribed in U.S. Pat. No. 3,492,330; polyisocyanates which containallophanate groups as described e.g. in British Pat. No. 994,890;Belgian Pat. No. 761,626 and published Dutch Patent Application No.7,102,524; polyisocyanates which contain isocyanurate groups asdescribed e.g. in German Pat. Nos. 1,022,789; 1,222,067 and 1,027,394and in German Offenlegungsschriften Nos. 1,929,034 and 2,004,048;polyisocyanates which contain urethane groups as described e.g. inBelgian Pat. No. 752,261 or in U.S. Pat. No. 3,394,164; polyisocyanateswhich contain acylated urea groups in accordance with German Pat. No.1,230,778; polyisocyanates which contain biuret groups as described e.g.in German Pat. No. 1,101,394; in British Pat. No. 889,050 and in FrenchPat. No. 7,017,514; polyisocyanates which are prepared by telomerizationreactions as described e.g. in Belgian Pat. No. 723,640; polyisocyanateswhich contain ester groups as described e.g. in British Pat. Nos.956,474 and 1,072,956; in U.S. Pat. No. 3,567,763 and in German Pat. No.1,231,688; and reaction products of the above mentioned isocyanates withacetals according to German Pat. No. 1,072,385.

Aromatic isocyanates are preferred for the purpose of the invention.

The distillation residues obtained from the commercial production ofisocyanates such as polymers of 4,4'-diphenylmethane diisocyanate whichstill contain isocyanate groups may also be used, and may be dissolvedin one or more of the above mentioned polyisocyanates. Any mixtures ofthe above mentioned polyisocyanates may also be used.

It is generally particularly preferred to use commercially readilyobtainable organic polyisocyanates such as tolylene-2,4- and-2,6-diisocyanate and any mixtures of these isomers (TDI);polyphenyl-polymethylene-polyisocyanates which can be obtained byaniline-formaldehyde condensation followed by phosgenation (crude MDI)and polyisocyanates which contain carbodiimide, urethane, allophanate,isocyanurate, urea or biuret groups (modified polyisocyanates).

It is also particularly advantageous to use, as polyisocyanates, theundistilled phosgenation products of tolylenediamine or mixtures of 2,4-and/or -2,6-tolylene diisocyanate and 5-60% by weight, preferably 10-50%by weight of the distillation residue obtained from the production oftolylene diisocyanate as well as mixtures of polyisocyanates which areobtained by the condensation of aniline with formaldehyde followed byphosgenation and 5% to 50% by weight, preferably 10% to 30% by weight,of the distillation residue obtained from the production of tolylenediisocyanate. The reason why these products are preferred is that it hasbeen found that the catalysts according to the invention are notattacked by the azide compounds and, particularly, chlorine compoundspresent in crude isocyanate mixtures, e.g. in crude tolylenediisocyanate or crude diisocyanatodiphenyl methane.

According to the invention, it is often preferred to include up to 50equivalents percent, based on the quantity of isocyanate, of compoundswith a molecular weight of about 62 to about 10,000 which contain atleast two hydrogen atoms which are reactive with isocyanates, e.g.ethylene glycol, propylene-1,3-glycol, hexane-1,6-diol, tripropyleneglycol or polypropylene glycol with a molecular weight of about 400.

Among the compounds which contain at least two hydrogen atoms which arereactive with isocyanates, those with a molecular weight of from about400 to about 10,000 are generally preferred. In addition to compoundswhich contain amino, thiol or carboxyl groups, the compounds of thiskind are preferably polyhydroxyl compounds, in particular those whichcontain 2 to 8 hydroxyl groups and especially those with a molecularweight of about 800 to about 10,000, preferably 1000 to 6000, e.g.polyesters, polyethers, polythioethers, polyacetals, polycarbonates andpolyester amides which contain at least 2 and generally 2 to 8 butpreferably 2 to 4 hydroxyl groups; these compounds are known per se forthe production of homogeneous and cellular polyurethanes.

Any suitable hydroxyl polyester may be used, for example, productsobtained by reacting polyhydric alcohols, preferably dihydric alcoholsto which trihydric alcohols may be added, with polybasic, preferablydibasic carboxylic acids. Instead of free polycarboxylic acids, thecorresponding polycarboxylic acid anhydrides or correspondingpolycarboxylic acid esters of lower alcohols or mixtures thereof may beused for preparing the polyesters. The polycarboxylic acids may bealiphatic, cycloaliphatic, aromatic and/or heterocyclic and may besubstituted, e.g. with halogen atoms and/or unsaturated. The followingare examples: succinic acid; adipic acid; suberic acid; azelaic acid;sebacic acid; phthalic acid; isophthalic acid; trimellitic acid;phthalic acid anhydride; tetrahydrophthalic acid anhydride;hexahydrophthalic acid anhydride, tetrachlorophthalic acid anhydride,endomethylene tetrahydrophthalic acid anhydride; glutaric acidanhydride; maleic acid; maleic acid anhydride; fumaric acid; dimeric andtrimeric fatty acids such as oleic acid which may be mixed withmonomeric fatty acids, dimethyl terephthalate and bis-glycolterephthalate. The following are examples of suitable polyhydricalcohols: ethylene glycol; propylene-1,2- and -1,3-glycol; butylene-1,4-and -2,3-glycol; hexane-1,6-diol; octane-1,8-diol, neopentyl glycol;cyclohexane dimethanol (1,4-bis-hydroxymethylcyclohexane);2-methyl-propane-1,3-diol; glycerol; trimethylolpropane;hexane-1,2,6-triol, butane-1,2,4-triol; trimethylolethane;pentaerythritol; quinitol; mannitol and sorbitol; methyl glycoside,diethylene glycol; trimethylene glycol; tetraethylene glycol;polyethylene glycols, dipropylene glycol; polypropylene glycols,dibutylene glycol and polybutylene glycols. The polyesters may contain aproportion of carboxyl end groups. Polyesters of lactones such asε-caprolactone or hydroxycarboxylic acids such as ω-hydroxycaproic acidmay also be used.

Any suitable polyether which contains at least two and generally 2 to 8,preferably 2 or 3 hydroxyl groups may be used. Such polyethers are knownper se and are prepared e.g. by polymerizing epoxides such as ethyleneoxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxideor epichlorohydrin with themselves, e.g. in the presence of borontrifluoride, or by a process of addition of these epoxides, either asmixtures or successively, to starting components which contain reactivehydrogen atoms such as alcohols or amines, e.g. water, ethylene glycol,propylene-1,3- or -1,2-glycol, trimethylolpropane,4,4'-dihydroxy-diphenylpropane, aniline, ammonia, ethanolamine orethylene diamine. Sucrose polyethers, e.g. those described in GermanAuslegeschriften Nos. 1,176,358 and 1,064,938, may also be usedaccording to the invention. It is frequently preferred to use thosepolyethers which contain predominantly primary hydroxyl groups (up to90% by weight, based on all the hydroxyl groups present in thepolyether). Polyethers which have been modified with vinyl polymers,e.g. the products obtained by polymerizing styrene or acrylonitrile inthe presence of polyethers (U.S. Pat. Nos. 3,383,351; 3,304,273;3,523,093 and 3,110,695 and German Pat. No. 1,152,536) andpolybutadienes which contain hydroxyl groups are also suitable.

Any suitable polythioether may be used such as, for example, thecondensation products of thiodiglycol with itself and/or with otherglycols, dicarboxylic acids, formaldehyde, aminocarboxylic acids oraminoalcohols. The products obtained are either polythio mixed ethers,polythioether esters or polythioether ester amides, depending on theco-component.

The polyacetals used may be, for example, the compounds which can beprepared from glycols such as diethylene glycol, triethylene glycol,4,4'-dioxethoxy-diphenyldimethylmethane, hexanediol and formaldehyde.Polyacetals suitable for the purpose of the invention may also beprepared by polymerizing cyclic acetals.

Any suitable polycarbonate with hydroxyl groups may be used such as thekind known per se which can be prepared, for example, by reacting diolssuch as propane-1,3-diol, butane-1,4-diol and/or hexane-1,6-diol,diethylene glycol, triethylene glycol or tetraethylene glycol withdiarylcarbonates, e.g. diphenyl carbonate or phosgene.

Suitable polyester amides and polyamides include e.g. the predominantlylinear condensates obtained from polyvalent saturated and unsaturatedcarboxylic acids or their anhydrides and polyvalent saturated andunsaturated amino alcohols, diamines, polyamines and their mixtures.

Polyhydroxyl compounds which already contain urethane or urea groups aswell as natural polyols which may be modified such as castor oil,carbohydrates or starch may also be used. Addition products obtained byreacting alkylene oxides with phenol formaldehyde resins or with ureaformaldehyde resins may also be used according to the invention.

Representatives of these compounds which may be used according to theinvention have been described e.g. in High Polymers, Vol. XVI,"Polyurethanes, Chemistry and Technology" by Saunders-Frisch,Interscience Publishers, New York, London, Volume I, 1962, pages 32-42and pages 44-54 and Volume II, 1964, pages 5-6 and 198-199 and inKunststoff-Handbuch, Volume VII, Vieweg-Hochtlen, publishersCarl-Hanser-Verlag, Munich, 1966, e.g. on pages 45 to 71.

Water and/or any suitable readily volatile organic substance may be usedas a blowing agent in addition to the carbon dioxide liberated by theformation of polycardodiimide. Suitable organic blowing agents are e.g.acetone, ethyl acetate, methanol, ethanol, halogenated alkanes such asmethylene chloride, chloroform, ethylidene chloride, vinylidenechloride, monofluorotrichloromethane, chlorodifluoromethane ordichlorodifluoromethane, butane, hexane, heptane, or diethyl ether.Compounds which decompose at temperatures above room temperature toliberate gases such as nitrogen, e.g. azo compounds such as azoisobutyric acid nitrile, may also act as blowing agents. Other examplesof blowing agents and details of the methods of using them may be foundin Kunststoff-Handbuch, Volume VII, published by Vieweg and Hochtlen,Carl-Hanser-Verlag, Munich 1966, e.g. on pages 108 and 109, 453 to 455and 507 to 510.

According to the invention, the catalysts commonly used in isocyanatechemistry may be used in addition to the addition compounds according tothe invention. The following are examples of conventional catalystswhich may be used along with the catalysts according to the invention:tertiary amines such as triethylamine; tributylamine;N-methyl-morpholine; N-ethyl-morpholine; N-cocomorpholine;N,N,N',N'-tetramethyl-ethylene diamine;1,4-diaza-bicyclo-(2,2,2)-octane;N-methyl-N'-dimethyl-aminoethyl-piperazine; N,N-dimethylbenzylamine;bis-(N,N-diethylaminoethyl)-adipate; N,N-diethylbenzylamine,pentamethyl-diethylene triamine; N,N-dimethylcyclohexylamine;N,N,N',N'-tetramethyl-1,3-butanediamine;N,N-dimethyl-β-phenyl-ethylamine; 1,2-dimethylimidazole and2-methylimidazole.

The following are examples of suitable tertiary amine catalysts whichcontain hydrogen atoms that react with isocyanate groups:triethanolamine; triisopropanolamine; N-methyl-diethanolamine;N-ethyl-diethanolamine; N,N-dimethyl-ethanolamine and their reactionproducts with alkylene oxides such as propylene oxide and/or ethyleneoxide.

Silaamines which contain carbon-silicon bonds may also be used ascatalysts, e.g. the compounds described in German Pat. No. 1,229,290such as 2,2,4-trimethyl-2-silamorpholine or1,3-diethylaminomethyltetramethyl-disiloxane.

Bases which contain nitrogen, such as, tetraalkylammonium hydroxides,alkali metal hydroxides such as, sodium hydroxide, alkali metalphenolates such as sodium phenolate and alkali metal alcoholates such assodium methylate may also be used as catalysts. Hexahydrotriazines arealso suitable catalysts.

According to the invention, organic metal compounds may also be used ascatalysts, especially organic tin compounds.

The organic tin compounds preferably used are the tin(II) salts ofcarboxylic acids such as tin(II) acetate, tin(II) octoate, tin(II)ethylhexoate and tin(II) laurate and the dialkyl tin salts of carboxylicacids such as dibutyl tin diacetate, dibutyl tin dilaurate, dibutyl tinmaleate or dioctyl tin diacetate.

Other examples of catalysts to be used according to the invention anddetails of their mode of action may be found in Kunststoff-Handbuch,Volume VII, published by Vieweg and Hochtlen, Carl-Hanser-Verlag, Munich1966, e.g. on pages 96 to 102.

Any catalytic amount of the usual catalysts of isocyanate chemistry maybe used such as, for example, between about 0.001% and 10% by weight,based on the quantity of compounds with a molecular weight of 400 to10,000 which contain at least two hydrogen atoms that are reactive withisocyanates.

Surface active additives (emulsifiers and foam stabilizers) may also beused according to the invention. The emulsifiers used may be e.g. thesodium salts of ricinoleic sulphonates or of fatty acids or salts offatty acids with amines such as oleic acid diethylamine or stearic aciddiethanolamine. Alkali metal or ammonium salts of sulphonic acids suchas the alkali or ammonium salts of dodecyl benzene sulphonic acid or ofdinaphthylmethane disulphonic acid or of fatty acids such as ricinoleicacid or of polymeric fatty acids may also be used as surface activeadditives.

The foam stabilizers used are mainly water-soluble polyether siloxanes.These compounds are generally constructed so that a copolymer ofethylene oxide and propylene oxide is attached to a polydimethylsiloxanegroup. Foam stabilizers of this kind have been described, for example,in U.S. Pat. No. 3,629,308 the disclosure of which is incorporatedherein by reference.

Reaction retarders, e.g. substances which are acid in reaction such ashydrochloric acid or organic acid halides, cell regulators known per sesuch as paraffins or fatty alcohols or dimethylpolysiloxanes, pigments,dyes and flame retarders known per se, e.g. tris-chloroethylphosphate orammonium phosphate and polyphosphate, stabilizers against ageing andweathering, plasticizers, fungistatic and bacteriostatic substances andfillers such as barium sulphate, kieselguhr, carbon black or whiting mayalso be used according to the invention.

Other examples of surface active additives, foam stabilizers, cellregulators, reaction retarders, stabilizers, flame retarding substances,plasticizers, dyes and fillers and fungistatic and bacteriostaticsubstances which may also be used according to the invention and detailsconcerning their methods of use and mode of action may be found inKunststoff-Handbuch, Volume VI, published by Vieweg and Hochtlen,Carl-Hanser-Verlag, Munich 1966, e.g. on pages 103 to 113.

In certain cases, e.g. when foaming undistilled phosgenation products oftolylene diamine, it may be advantageous to use 0.5% to 20% by weight,preferably 1% to 10% by weight, based on the quantity of isocyanate, ofisocyanurate-forming catalysts known per se in addition to the additioncompounds according to the invention.

The catalysts used for the formation of isocyanaurate groups arepreferably those which cause gelling of the isocyanate with isocyanurateformation at a temperature of 20° C. within 10 minutes when added in aquantity of 1 to 10 g per 100 g of organic polyisocyanate, e.g. sodiumphenolate, potassium acetate, sodium trichlorophenolate,2,4,6-tri-(dimethylaminomethyl) phenol or a mixture of 80% of ortho- and20% of para-dimethylaminomethylphenol.

The foam plastics which can be produced according to the invention haveexcellent flame resistance which can be even further improved by usingknown flame retarding agents such as compounds of halogens, of nitrogen,of phosphorus and of antimony.

Foaming may be carried out either by hand or mechanically by knowntechniques. Mechanical devices in which a mixture of activator andaddition compound, foaming agent, to which polyols, blowing agents andflame-retarding agents, etc. may be added and the isocyanate componentare delivered through separate pumps are advantageously used.

The foams according to the invention may be produced e.g. in the form ofblocks, panels or endless webs, either intermittently or continuously,if desired also on double conveyor belts. Foams which have been producedby foaming without restriction of volume generally have a density of 5to 25 kg/m³ while foams which have been produced by foaming in a closedmold may have a density of 25 to 100 kg/m³.

The foams containing carbodiimide groups are suitable for various typesof insulation against cold and heat. Because of their excellent flameresistance, they are particularly suitable for use as insulation inwalls of buildings and because of their high thermal resistance they arealso suitable for the insulation of technical plants, particularlyheating installations.

EXAMPLE 1 ##STR6##

6.8 g of oxo-1,2,2,3,4,4-hexamethyl-phosphetane and 150 ml of chloroformare introduced into a three-necked flask with stirrer and droppingfunnel. 4 ml of phosphorus oxychloride are then added dropwise withconstant stirring.

The reaction is exothermic. After termination of the reaction thechloroform is evaporated off. 12.8 g of a pale pink solid substancewhich melts at 189° C. are obtained.

The band position of the methyl group on phosphorus is shifted by 2.95ppm compared with the phosphetane used as starting material (solvent CDCl₃).

EXAMPLE 2 ##STR7##

8.7 g of 1-oxo-1,2,2,3,4,4-hexamethylphosphetane, 3.1 g of ethyleneglycol and 150 ml of chloroform are introduced into a flask withstirrer. The reaction mixture is heated to 20° to 30° C. with stirring.The reaction is exothermic. After termination of the reaction, thechloroform is evaporated off under vacuum and 10 g of a pale yellowishoil are obtained. The band position of the methyl protons on phosphorushas shifted to 1.63 ppm (solvent CD Cl₃).

EXAMPLE 3 ##STR8##

8.7 g of 1-oxo-1,2,2,3,4,4-hexamethyl-phosphetane, 6.8 g of zincchloride and 150 ml of chloroform are reacted together as in Example 2.After removal of the chloroform by evaporation, 16 g of a violet coloredaddition compound are obtained. The methyl proton signal of the groupattached to phosphorus has shifted to 1.84 ppm in this compound.

EXAMPLE 4 ##STR9##

8.7 g of 1-oxo-1,2,2,3,4,4-hexamethyl-phosphetane, 30 ml of 37% aqueoushydrogen chloride and 150 ml of chloroform are reacted together as inExample 2. Water and chloroform are then evaporated off under vacuum. Anoily addition compound is obtained. The band position of the methylprotons on the group attached to phosphorus is shifted to 1.8 ppm.

EXAMPLE 5

30 g of the addition compound described in Example 2 are heated to 50°C. in a three-necked flask equipped with reflux condenser, thermometerand stirrer. 50 g of glycerol are then added dropwise in portions (2 to3 g/min) with constant stirring. The reaction mixture is then heated to100° C. for 2 hours. An oily product is obtained after cooling to roomtemperature.

A mixture of 8 g of the adduct described above and 0.5 g of apolysiloxane-polyalkylene glycol (as foam stabilizer) is prepared in apaper cup. 100 g of polymeric diphenylmethane diisocyanate (obtained bycondensation of aniline with formaldehyde followed by phosgenation)which has a viscosity of 200 cP/35° C. and an isocyanate content of31.2% are added to this mixture with vigorous stirring.

    ______________________________________                                        Reaction times:                                                                           .sup.+ R = 120 sec                                                                          .sup.+ R = stirring time                                        .sup.+ I = 170 sec                                                                          .sup.+ I = lying time                                           .sup.+ A = 610 sec                                                                          .sup.+ A = setting time                                         .sup.+ S = 730 sec                                                                          .sup.+ S = rising time                                          .sup.+ K = 780 sec                                                                          .sup.+ K = tack-free time                           ______________________________________                                    

The foam obtained has the following physical properties

    ______________________________________                                        Density:         19 kg/m.sup.3 DIN 53420                                      Compression strength:                                                                          1.1 kg/cm.sup.2 DIN 53421                                    Resistance to bending                                                          under heat:     125° C. DIN 53424                                     Coefficient of thermal                                                                         0.029 kcal/m/h/degree                                         conductivity:   DIN 52612                                                    Small sample burning                                                           test:           77-85 Fl, Kl DIN 4102                                        ______________________________________                                    

Pure 1-oxo-1,2,2,3,4,4-hexamethylphosphetane causes such a rapidreaction that homogeneous mixing of polyisocyanate with catalyst anddischarge of the mixture involves great difficulties.

Any of the other addition compounds indicated as suitable as catalystsmay be substituted for the one used in Example 5 and other organicpolyisocyanates can be used instead of the poly (diphenylmethanediisocyanate) if desired.

Although the invention has been described in detail for the purpose ofillustration, it is to be understood that such detail is solely for thatpurpose and that variations can be made therein by those skilled in theart without departing from the spirit and scope of the invention exceptas it may be limited by the claims.

What is claimed is:
 1. An addition compound which is the reactionproduct of (a) a phosphetane oxide or phosphetane sulphide of theformulae I and II: ##STR10## wherein X is selected from the groupconsisting of C₁ -C₁₈ alkyl, C₂ -C₁₈ alkenyl, C₆ -C₁₄ aryl, C₇ -C₂₀aralkyl, C₁ -C₁₈ alkoxy and C₆ -C₁₄ aroxy, and wherein R¹ to R⁶ areselected from the group consisting of hydrogen and C₁ -C₄ alkyl, and(b)a compound selected from the group consisting of(i) aliphatic mono- di-and polyhydric alcohols having molecular weights of from about 32 toabout 250, (ii) protonic acids having pH's of between 1 and 8 in N/10aqueous solution, (iii) metal salts selected from the group consistingof zinc chloride, tin (II) bromide, tin (IV) chloride, magnesiumchloride, calcium chloride, lithium chloride, lithium iodide, cadmiumchloride, manganese (II) chloride, zinc acetate, vanadiumoxythrichloride, and aluminum chloride, and (iv) acid chlorides selectedfrom the group consisting of phosphorous (III) chloride, phosphorousoxytribromide, phosphorous oxychloride, antimony (V) chloride, silicon(IV) chloride, methyl trichlorosilane, methane phosphonic aciddichloride, methane sulphonic acid chloride, p-toluene sulphonic acidchloride, and 1-chloro-1-oxophospholine.
 2. A process for preparing anaddition compound which contains phosphorous which comprises reacting ina molar ratio of 1:20 to 21:1, (a) a phosphetane oxide or phosphetanesulphide of the formulae I or II: ##STR11## wherein x is selected fromthe group consisting of C₁ -C₁₈ alkyl, C₂ -C₁₈ alkenyl, C₆ -C₁₄ aryl, C₇-C₂₀ aralkyl, C₁ -C₁₈ alkoxy and C₆ -C₁₄ aroxy, and wherein R¹ to R⁶ areselected from the group consisting of hydrogen and C₁ -C₄ alkyl, and(b)a compound selected from the group consisting of(i) aliphatic mono- di-and polyhydric alcohols having melecular weights of from about 32 toabout 250, (ii) protonic acids having pH's of between 1 and 8 in N/10aqueous solution, (iii) metal salts selected from the group consistingof zinc chloride, tin (II) bromide, tin (IV) chloride, magnesiumchloride, calcium chloride, lithium chloride, lithium iodide, cadmiumchloride, manganese (II) chloride, zinc acetate, vanadiumoxytrichloride, and aluminum chloride, (iv) acid chlorides selected fromthe group consisting of phosphorous (III) chloride, phosphorousoxytribromide, phosphorous oxychloride, antimony (V) chloride, silicon(IV) chloride, methyl trichlorosilane, methane phosphonic aciddichloride, methane sulphonic acid chloride, p-toluene sulphonic acidchloride, and 1-chloro-1-oxophospholine.
 3. An addition compound whichis the reaction product of:(a) 1-oxo-1,2,2,3,4,4-hexamethyl phosphetane,and; (b) a compound selected from the group consisting of ethyleneglycol, glycerol, oxalic acid, phosphorous oxychloride, hydrochloricacid and zinc chloride.